[InstCombine] Transform `(binop1 (binop2 (lshift X,Amt),Mask),(lshift Y,Amt))`

If `Mask` and `Amt` are not constants and `binop1` and `binop2` are
the same we can transform to:
`(binop (lshift (binop X, Y), Amt), Mask)`

If `binop` is `add`, `lshift` must be `shl`.

If `Mask` and `Amt` are constants `C` and `C1` respectively.
We can transform to:
`(lshift1 (binop1 (binop2 X, (inv_lshift1 C, C1), Y)), C1)`

Saving an instruction IFF:
`lshift1` is same opcode as `lshift2`
Either `bitwise1` and/or `bitwise2` is `and`.

Proofs(1/2): https://alive2.llvm.org/ce/z/BjN-m_
Proofs(2/2): https://alive2.llvm.org/ce/z/bZn5QB

This is to help fix the regression caused in D151807

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D152568